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HOW TO MAKE GOO
How to Make Good Waterproofed Concrete
With Medusa Waterproofed Gray Portland Cement
Medusa Portland Cement Company • 1000 Midland Bldg., Cleveland, 0.
Sales Oiiices: New York, N. Y. • Chicago, 111. • Grand Rapids, Mich. • Manitowoc,
Wis. • Cleveland, O. • Pittsburgh, Pa. • Washington, D. C. • York, Pa. • Toledo, O.
Copyright Medusa Portland Cement Co. 1939
Printed in U. S. A.
Why the Name Medusa?
When Perseus was grown up, Polydecies sent him io atiempi the conquest of the
Gorgon Medusa, a terrible monster who had laid waste the country. She had once
been a maiden whose hair was her chief glory, but as she dared to vie in beauty with
Minerva, the Goddess deprived her of her charms and changed her ringlets into hissing
serpents. She became a monster of so frightful an aspect thai no living thing could
behold her without being turned into stone. All around the cavern where she dwelt
might be seen the stony figures of men and animals that had chanced to catch a
glimpse of her and had been petrified at the sight. ♦ Perseus, favored by Minerva and
Mercury, set out against the Gorgon and approached first the cave of the three Graeae.
Here the three old crones with their single eye sat bemoaning their lot. Snatching the
eye, Perseus compelled the Graeae, at the price of its restoration, to tell him how he
might obtain the Helmet of Hades, thai renders its wearer invisible, and the winged
shoes and pouch that were necessary. With this outfit, to which Minerva added her
shield and Mercury his knife, Perseus sped to the hall of the Gorgons. In silence sat
two of the sisters— but the third paced about the hall moaning and shrieking in despair
because the golden tresses of her hair were moved by writhing snakes from side io
side. This was Medusa. While she was praying the gods to end her misery, or, as some
say, while she was sleeping, Perseus approached, and, guided by her image reflected
in the bright shield which he bore, cut off her head and so ended her miserable ex-
istence. The head itself he bestowed upon Minerva, who bore it afterwards upon her
aegis, or shield. That is the story of Medusa. ♦ Years ago when our company was in
search of a good brand name, Medusa, the name of the fabled woman of Greek
mythology whose glance turned living creatures to stone was selected as most ap-
propriate for our cement products. What could better symbolize the modern magic by
which Medusa Portland Cement creates great edifices and engineering works as solid
as the native rock? We believe that few products are so significantly named. And
so the name Medusa, applied to products made by the Medusa Portland Cement
Company of Cleveland, lives today and her magic power survives most beneficently,
atoning for her malevolence by creating useful structures for the benefit of mankind.
Duke University, Durham, North Carolina
Horace Trumbauer, Philadelphia, Architect A. C. Lea, Chief Engineer
E. H. Clement Co., Charlotte and Durham, N. C, Stone Contractors
Medusa products furnished by W. C. Lyon Co., Durham, N. C.
Medusa Waterproofed Gray Portland Cement and Medusa Waterproofed White Portland Cement were used in the construction of this large project.
WHY Concrete, stucco and masonry, including mortar, should
be waterproofed during the original construction
• For centuries past and to come, concrete has
been and will continue to be one of man's most
dependable and useful building materials. This
dependence in concrete is due to its flexibility
in application and its strength and ability to with-
stand the most severe construction conditions.
Concrete is usually exposed to water and mois-
ture, ground acids and alkalies as well as acid
fumes in the air. It is subject to freezing and thaw-
ing actions brought about by changes of tem-
perature and the elements.
Because of its naturally sturdy, strong character,
concrete withstands these severe conditions bet-
ter than most other types of construction materi-
als. However, even the naturally long life of
concrete can be greatly extended if it is water-
proofed for protection.
Waterproofed concrete means concrete that suc-
cessfully repels water at the surface. Water-
proofed concrete should not be confused with
water tight concrete. In the latter case the con-
crete may absorb water but the water does not
necessarily travel completely through the con-
The more water concrete absorbs, the sooner the
concrete will need maintenance or replacement.
Water absorbed into tiny crevices or cracks is
subject to freezing. Freezing water expands with
a terrific force which widens these liny pores
and crevices and deterioration starts in. If con-
crete is waterproofed, the water is repelled at the
surface and thus the deteriorating action caused
by freezing of the absorbed water is prevented.
WATER DAMAGE - The absorption of water
through a concrete wall or through the mortar
joints in masonry construction may cause con-
siderable damage. Most frequently this damage
consists of the ruining of plaster and interior
decorations and damaging interior wood mold-
ing, floors, linoleum, carpets, etc.
MAINTENANCE— The maintenance of concrete,
stucco or masonry walls when once absorption
of water takes place is expensive and continu-
ous. Thai's why it is highly important that these
types of construction should be waterproofed
during the original construction. A few addi-
tional dollars spent for waterproofed concrete,
stucco and mortar at the time of building means
only a very small percentage added to the cost,
whereas unwaterproofed construction thai ab-
sorbs moisture may be the cause of spending
in repairs and damage, many, many times the
cost of waterproofing during construction. It is
always less expensive to waterproof during
SANITATION - Interior walls and floors that
have become damp through lack of waterproof-
ing give rise to musty odors that frequently
contaminate merchandise and produce mildew
and rust, and oftentimes are conducive to disease.
For these reasons, public health officials do not
approve damp conditions in buildings used for
habitation or work.
In the pages of this book we have covered the
use and specifications for waterproofing many
specific types of construction with Medusa
Waterproofed Gray Portland Cement. This
cement is mixed and used the same way as regu-
lar Gray Portland Cement and meets and ex-
ceeds all specifications for regular Gray Port-
WATERPROOFED Cement has these advantages
Medusa Waterproofed Gray Portland Cement is
a true waterproofed cement. That is, it is our
regular Medusa Gray Portland Cement to which
has been added the correct amount of Medusa
Waterproofing, mechanically ground in during
the process of manufacture, thereby insuring a
complete distribution of the waterproofing
throughout the cement. This means that Medusa
Waterproofed Gray Portland Cement will give
the maximum waterproofing value. The use of
a waterproofed cement— that is a cement with
the correct amount of waterproofing added at
the mill during the process of manufacture-has
a number of decided advantages over adding a
waterproofing material to the cement at the time
of mixing on the job.
The contractor or builder likewise benefits from
the use of waterproofed cement in that he, too,
has less supervision and one less material to
handle on the job. Medusa Waterproofed Gray
Portland Cement requires no special effort to
handle, since it is used the same as regular Gray
The most vitally interested party, however, is
the owner and he should insist that Medusa
Waterproofed Gray Portland Cement be used in
his work. The use of this cement assures him of
permanent waterproofing at a very small ad-
Let us emphasize that it does not require any
special knowledge to use Medusa Waterproofed
Gray Portland Cement. Anyone who knows how
chool Winston-Salem, North Carolina Harold Mackhn, Architect
Medusa Waterproofed Gray
Today most architects prefer a waterproofed
cement because it eliminates the supervision
necessary to insure the proper amount of water-
proofing is used. The specification, therefore, of
Medusa Waterproofed Gray Portland Cement
eliminates the human-element hazard always
present when waterproofing agents are added
on the job. This means the resulting concrete is
sure to be permanently waterproofed and the
F. L. Blum & Co., Contractors
Portland Cement used.
Standard Supply Co., Dealer
to make good concrete can make good water-
proofed concrete with Medusa Waterproofed
Gray Portland Cement. There is no question as
to the waterproofing efficiency of this cement.
It has a service record of 32 years, having been
used in countless jobs below and above grade
under unusually severe conditions, and has
been thoroughly tested in concrete as well as in
mortar for laying up brick, tile, concrete blocks,
PROVING the value of Medusa Waterproofing
Three concrete blocks— left made with regular cement, center with Medusa Waterproofed Gray
Portland Cement and right with Medusa Concentrated Waterproofing Paste— were placed in pans
which were filled with water.
In 15 minutes water has risen by capillary attraction half-way up the unwalerproofed block. The
Medusa Waterproofed blocks show no rise because the water was repelled at the surface of the concrete.
At the end of an hour the unwalerproofed block was wet all over and the Medusa Waterproofed
blocks were dry, proving the efficiency of Medusa Waterproofed Gray Portland Cement and Medusa
Concentrated Waterproofing Paste in slopping absorption of water at the surface of the concrete blocks.
ESSENTIALS of good waterproofed concrete
CONCRETE-Concrete is a mixture of porlland
cement, water and mineral aggregates placed
in a plastic condition but hardening soon after,
due to the process known as hydration of the
cement. Since concrete is placed in a plastic
condition, it cannot be tested for quality at the
time of fabrication. However, by proper control
of the proportioning, mixing and placing to-
gether with the subsequent curing, it is possible
to produce concrete of any quality to meet the
requirements of the work.
The fundamental requirements of hardened con-
crete are strength, waterproofness, durability
and economy. Fresh concrete must be workable,
that is, it must be of such consistency and physi-
cal make-up that it can be readily placed in the
form without segregation of the materials and
without requiring an excessive amount of spad-
ing to completely fill the form. Uniformity in the
fresh concrete is necessary to secure durability
of concrete, to facilitate handling and placing
and to obtain uniformity in the complete struc-
ture. It is particularly important where water-
proofness is required.
STRENGTH— Most concrete design is based on
compressive strength. However, the flexural and
tensile strength, the bond with steel reinforce-
ment, and the resistance to wear are in general
governed by the same factors that govern the
compressive strength. The compressive strength,
therefore, may be used as an indication of these
other qualities and, since the test for compres-
sive strength is comparatively simple, it is the
test that is most often adopted.
DURABILITY— If structures are to give long ser-
vice, the durability of the materials is just as
important as the strength. In the past this has
not been fully appreciated and too much empha-
sis has been placed on strength and economy
alone. The most important factor affecting dura-
bility of exposed concrete is its waterproofness.
A concrete that will stand up for a long time re-
quires sound, durable aggregates thoroughly
incorporated in a waterproofed cement paste.
ECONOMY— While economy of materials is im-
portant, there are other factors affecting the
economy of concrete which should receive more
consideration. The amount of labor required in
placing and finishing concrete is a considerable
item in the total cost. Labor cost is lowest when
the mixture used is most easily placed. The ease
of placing varies with the plasticity of the mix.
The most economical concrete is not the mix
having the lowest cement factor nor the mix
with the lowest cost for materials, but is the mix
for which total cost— materials, handling and
placing— is the lowest.
WORKABILIT Y-The workability required varies
with different classes of work and is determined
by the methods of transporting and the details
of placing— width and depth of forms and spac-
ing of reinforcement. Plastic concrete may be
regarded as a mass of aggregate particles, indi-
vidually floated in a cement paste. This gives a
mass that can be transported without segrega-
tion and can be placed easily in such a manner
that when the forms are removed the hardened
concrete will have smooth surfaces, free from
honeycombing. Concrete of such consistency
requires a minimum amount of finishing. In
much of the practice in the past, such concrete
has not been obtained. This was largely due to
the fact that arbitrary mixtures were specified
which did not permit adjustments in the mix to
suit the character of materials, the condition in
which they were measured or the placing re-
quirements of the job. In the endeavor to obtain
workable mixtures, excess water was often
added which almost invariably resulted in seg-
regation, porosity and low strength. For direc-
tions on how to avoid these faults, see sub-heads
"Water" and "Mixing" under Specifications on
UNIFORMITY- Uniformity is important since all
parts of a structure designed for the same strength
should be made of concrete of the same quality.
Moreover, the best economy can be obtained only
by the use of uniform batches of concrete. Uni-
formity is best secured by using plastic concrete
made homogeneous by thorough mixing of uni-
formly measured quantities of materials.
(Upper Left) 1910 Pittsburgh Natatorium, Pitts-
burgh, Pa., F. A. Burden, New York. N. Y., Engineer.
Grosvenor Atterbury, New York, N. Y., Architect.
(Center Lefl) 1917 Inland Steel Company, Indiana
Harbor, Ind. Entrance to tunnels connecting Com-
pany's Plants No. 1 and No. 2. Brownell Improve-
ment Co., Chicago, 111., General Contractors.
(Lower Lefl) 1924 Northland Hotel, Green Bay, Wis.
Martin Tullgren 6 Sons, Milwaukee, Wis., Architects.
Tudolt, Hansen Const., Green Bay, Wis., Cement Work.
(Upper Right) 1923 Hotel Retlaw, Fond du lac. Wis.
Martin Tullgren & Sons, Milwaukee, Wis., Architects.
The Immel Const. Co., Fond du lac. Wis., Contractors.
(Center Right) 1918 Basement, Tr eleven Depart-
ment Store Building, Fond du Lac, Wis.
(Lower Right) 1922 Municipal Administration
Building, Kaukauna, Wisconsin. W. E. Reynolds,
Green Bay, Wisconsin, Architect. John Cop pes,
Kaukauna, Wis., Contractor.
WATERPROOFING Concrete and masonry below grade level
An actual photograph of a damp basement. The use of Medusa Water-
proofed Gray Portland Cement would have prevented this condition.
The above photograph was taken in a "typical"
damp or wet basement. This condition could
easily have been prevented had Medusa Water-
proofed Gray Portland Cement been used in the
concrete and mortar, and in exterior and interior
plaster coats. The exterior of all basement walls,
in fact any concrete or masonry below grade is
subject to ground water, ground acids and earth
dampness. The use of Medusa Waterproofed
Gray Portland Cement prevents wet basements.
Monolithic concrete construction for basement
walls and floors has many advantages over
other methods. The use of Medusa Waterproofed
Gray Portland Cement with this type of construc-
tion gives a waterproofness to the basement be-
cause a water repellent substance is incorpo-
rated integrally throughout the entire mass of
the concrete. The advantage of mill mixed water-
proofed cement containing the proper amount
of waterproofing uniformly distributed through-
out the cement can be secured by specifying
and using Medusa Waterproofed Gray Port-
PRECAST UNITS-When brick, stone or tile is
used as the construction unit for the wall, it is
imperative that these precast units be laid in a
mortar made with Medusa Waterproofed Gray
Portland Cement (see mortar specifications).
When concrete block is used, the blocks should
likewise be manufactured with Medusa Water-
proofed Gray Portland Cement and laid up with
waterproofed mortar made with Medusa Water-
proofed Gray Portland Cement according to
Waterproofing is particularly recommended for
all types of below grade construction such as
swimming pools, elevator pits, mine shafts, base-
ment caissons, etc. Medusa Waterproofed Gray
Portland Cement should be used for all these
types of construction and in fact, all concrete
and masonry below grade.
PROTECTING above grade level concrete, masonry
and stucco surfaces against disintegration
All above grade construction, whether it be of
concrete, stucco, brick, cinder blocks, concrete
bricks or any other type of masonry, should be
protected by waterproofing, especially if it is
exposed to the elements.
There are many causes of disintegration of ex-
posed surfaces. The freezing and the thawing
action of water absorbed by exposed surfaces is
very destructive and causes disintegration and
spoiling. The force exerted by the freezing of con-
fined water will break open a cannon ball. This
same terrific force is exerted when water ab-
sorbed into the pores and crevices of a wall
freezes. This may open up mortar joints and
leaky mortar joints permit the entrance of mois-
ture, destroying interior decorations and creat-
ing very unpleasant conditions.
Frequently acid fumes of the air combined with
rain water become a disintegrating factor when
absorbed into masonry, stucco or concrete walls.
Unwaterproofed mortar is a factor in the appear-
ance of white efflorescence which gives an un-
sightly appearance to masonry walls. It is
caused by absorbed water dissolving alkali
salts and then depositing them on the surface
when the water evaporates. The use of Medusa
Waterproofed Gray Portland Cement in stucco,
concrete, concrete bricks, blocks as well as in
mortar for laying up these and other masonry
units will prevent absorption of water through re-
pelling all water at the surface, thus stopping dis-
integration and efflorescence and prolonging the
life of concrete and masonry indefinitely. The
cost of waterproofing with Medusa Water-
proofed Gray Portland Cement is very small and
is only a fraction of the expense necessary in
maintaining and repairing leaky, damp, above
grade construction, consequently it is advis-
able to waterproof the original construction.
Dollar Savings & Trust Company Building
Press C. Dowler. Architect D. T. Riitle. Pittsburgh, Pa., Contractor
Hillside Stone & Supply Co.. Pittsburgh
Medusa Waterproofed Gray Portland Cement used m all the brick mortar
SPECIFICATIONS for waterproofing concrete
foundation walls and basement floors
PORTLAND CEMENT-To insure the uniformity
of the waterproofed cement, specify and use
Medusa Waterproofed Gray Portland Cement.
PROPORTIONS— The concrete shall be mixed in
the proportions of one sack of Medusa Water-
proofed Gray Portland Cement, two and one-half
cubic feet of fine aggregate, and three to four
cubic feet of coarse aggregate.
Where concrete must resist moisture or damp-
ness, the mix should never be any leaner than
1:2:4. Leaner mixes are more porous, being less
dense than the richer mixes.
The richer mixes should be used where greater
strength is required or where the exposure to
water is quite severe, such as sea water work,
swimming pools, large tanks or reservoirs.
AGGREGATE-Fine aggregate shall consist of
sand or screenings from crushed rock or pebbles,
well graded from fine to coarse, passing, when
dry, a screen having four meshes to the linear
inch. Fine aggregate shall not contain injurious
amounts of vegetable or other organic matter.
Coarse aggregate shall consist of hard crushed
rock or gravel, free from vegetable or other
organic matter, and shall be free from soft, flat or
elongated particles. It shall be well graded from
l A inch to one inch in size, not more than fifteen
per cent passing a screen having four meshes
per linear inch.
WATER-Jusi enough water should be used in
mixing the concrete as will give a plastic, work-
able consistency which can be economically
placed. An excess of water must be avoided. It
is recommended that not more than six gallons
of water be used per sack of cement.
MIXING-Medusa Waterproofed Gray Portland
Cement is used in a concrete mixer exactly the
same as regular portland cement. However,
proper mixing is made easier by pulling Iwo or
three gallons of water in the mixer before the
aggregate and cement are put in. The minimum
mixing time per batch is one and one-half min-
utes. The cement contains the proper percentage
of waterproofing. The contractor must not use
any more gauging water than will give a jelly-
like or mushy concrete. Concrete containing
sufficient water lo permit a settling or segrega-
tion of the heavier ingredients shall be rejected.
SPADING— Concrete must be thoroughly spaded
into place, well around reinforcing steel and
against the forms, so as to secure maximum
density by forcing out air and breaking up water
and stone pockets, preventing honeycombed
CURING-A11 concrete should be kept wet con-
tinuously for a period of at least seven days.
Unlike regular cement, once waterproofed ce-
ment dries out it repels all water at the surface,
hence cannot be wel again for proper curing.
FLOORS-Where two-course basement floors
are to be used the slab should be thick enough
and sufficiently reinforced to resist the upward
pressure of any water that may gather under
the floors. Concrete should be no leaner than a
1:2:4 proportion, mixed with a minimum amount
of water and properly placed upon a well
tamped cinder or rock fill which has been satu-
rated before the concrete is poured.
Whether the 1" or 2" finished topping of a two-
course floor should be waterproofed will depend
upon the use the floor will have. Oftentimes it is
sufficient lo waterproof only the slab.
For lopping see page 14, Specifications tor
bonded Concrete Floor Finish.
Where water conditions surrounding a house or
building are not taken care of by drain tile, the
concrete floors should be reinforced with steel
bars, wire mesh or expanded metal mesh suffi-
ciently to overcome lhe pressure of water which
may gather under the floor.
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SPECIFICATIONS foi bonded concrete floor finish
BASE SLAB— The surface of the structural base
slab shall be finished reasonably true and struck
off at a level not less than one inch below the
required finish grade.
As soon as the condition of the concrete base
permits and before it has fully hardened, all dirt,
laitance and loose aggregate shall be removed
from the surface by means of a wire broom,
which shall leave the coarse aggregate slightly
exposed, or the surface otherwise roughened to
improve bond with the lopping.
When impossible to remove laitance and rough-
en slab, surface shall be cleaned and prepared
for bond by chipping after base has hardened,
Just prior to placing the finish, the base slab
shall be thoroughly cleaned by scrubbing, to the
satisfaction of the engineer.
PORTLAND CEMENT-Portland cement shall be
Medusa Waterproofed Gray Portland Cement.
AGGREGATES-Boih fine and coarse aggregates
shall be used in the finish. Fine aggregates shall
consist of clean, hard sand or crushed stone
screenings free from dust, clay, loam or vegeta-
ble matter. All particles shall pass a Vi-inch
sieve and shall be graded from fine to coarse
with the coarse particles predominating. Not
more than five per cent shall pass a 100-mesh
sieve and not more than 15 per cent shall pass
a 50-mesh sieve.
Coarse aggregate shall consist of clean, hard
gravel or crushed stone free from dust, clay,
loam or vegetable matter and from coatings
which shall tend to weaken the bond. It shall con-
tain no soft, flat or elongated fragments and shall
be graded from Ve to 3 /e inch with not less than
95 per cent passing a 3 /e inch mesh sieve and not
more than 10 per cent passing a No. 8 sieve.
All aggregate shall be selected with care.
Coarse aggregate shall be of an approved
character and samples of proposed material
shall be submitted to the engineer for ap-
proval prior to use.
MIXTURE-The mixture shall be one part of
Medusa Waterproofed Gray Portland Cement,
one pari of fine aggregate and two parts oi
coarse aggregate by volume. This nominal mix
may be slightly varied, depending upon the local
conditions and as the engineer may direct. If the
aggregate is very coarse, the gravel or stone
may be reduced, but in no case shall the volume
of the coarse malenal be less than 1 1 2 times the
volume of the fine.
The mixture shall be determined by the engi-
neer and once established shall not be changed
except upon his written order.
Not more than five gallons of mixing water, in-
cluding the moisture in the aggregates, shall be
used for each sack of portland cement in the
Mixing of the concrete shall continue for at least
two minutes after all ingredients are in mixer.
CONSISTENCY-The concrete shall be of the
driest consistency possible to work with a saw-
ing motion of the strike-off board, or straight-
edge. Changes in consistency shall be obtained
by adjusting the proportions of fine and coarse
aggregate within the limits specified. In no case
shall the specified amount of mixing water
PLACING AND COMPACTING-The base slab
shall be thoroughly wetted just prior to the plac-
ing of the finish, but there shall be no pools of
water left standing on the wetted surface. A thin
coat of neat cement grout shall be broomed into
the surface of the slab for a short distance ahead
of the topping. The wearing course shall be im-
mediately applied before the grout has hard-
ened, and brought to the established grade with
a straightedge. After striking off the wearing
course to the established grade, it shall be com-
pacted by rolling or tamping, and then floated
with a wood float or power floating machine.
The surface shall be tested with a straightedge
to detect high and low spots, which shall be
FINISHING BY TROWELING-Floating shall be
followed by steel troweling after the concrete
has hardened sufficiently to prevent excess fine
material from working to the surface. The finish
shall be brought to a smooth surface free from
defects and blemishes. No dry cement nor mix-
ture of dry cement and sand shall be sprinkled
directly on the surface of the wearing course
to absorb moisture or to stiffen the mix. After the
concrete has further hardened, additional
troweling may be reguired. This shall be done
as may be directed by the engineer.
Note: Surfaces to be ground shall be swept with
soft brooms after rolling to remove any water
and surplus cement paste that may be brought
to the surface. The wearing course shall then be
floated and once lightly troweled, but no attempt
shall be made to remove all trowel marks.
FINISHING BY GRINDING-After the wearing
course has hardened sufficiently to prevent dis-
lodgemeni of aggregate particles, it shall be
ground down with an approved type of grind-
ing machine shod with free, rapid-cutting carbo-
rundum stones to expose the coarse aggregate.
The floor shall be kept wet during the grinding
process. All material ground off shall be re-
moved by squeegeeing and flushing with water.
Air holes, pits and other blemishes shall then be
filled with a thin grout composed of one part of
No. 80 grain carborundum grit and one part of
portland cement. This grout shall be spread over
the surface and worked into the pits with a steel
straight-edge, after which the grout shall be
rubbed into the floor surface with the grind-
After all patch fillers have hardened for seven
days, the floor surface shall receive a second or
final grinding to remove the film and to give the
finish a polish. It shall then be thoroughly
washed and all surplus material removed.
CURING AND PROTECTION-A11 freshly placed
concrete shall be protected from the elements
and from all defacement due to building oper-
ations. The contractor shall provide and use tar-
paulins when necessary to cover completely or
enclose all freshly finished concrete.
If at any time during the progress of work the
temperature is, or in the opinion of the engineer
will, within twenty-four hours, drop to 40 degrees
Fahrenheit, the water and aggregale shall be
heated and precautions taken to protect the
from freezing for at least three days.
As soon as the concrete has hardened to pre-
vent damage thereby, it shall be covered with at
least one inch of wet sand, or other covering
satisfactory to the engineer, and shall be kept
continually wet by sprinkling with water for at
least seven days.
WATERPROOFING mortar for masonry
SPECIFICATIONS-The following specifications
have been used on many buildings with per-
fectly satisfactory results.
The Waterproofed Portland Cement mortar shall
1 pari Medusa Waterproofed Gray Portland
3 parts clean, well-graded mason's sand
10 pounds hydrated lime per bag of cement,
or one-fifth part by volume of the cement
MIXING-If a contractor has the proper equip-
ment he will find it quite advantageous to have
his batches of mortar mixed ahead of time, using
just enough water in the preliminary mix to
make a damp earth consistency and allowing
Ihis mortar to set for any period of time up to one
hour after the mixing, and then when required
for use, more water is added to bring the mortar
to the proper consistency.
It has been found that mortar mixed in this way
has greater plasticity and workability than
freshly mixed mortar, as well as a greater ulti-
The increased workability and plasticity in the
mortar enables the mason to lay a greater
number of bricks in a given time than where
freshly mixed mortar is used, and this saving
in labor overcomes the slight expense involved
in running two mixing boxes.
Valley Stream High School Long Island, Frederick P. Wiedersum, Valley Stream, N. Y., Architect. Zerbe
Construction Co., New York City. Medusa Waterproofed Gray Cement used throughout brick work.
Allied Arts BIdg.. L ynch b li; I Weduso fa)
Gray PortlandCement used in /c.::^"-'« —
(Upper Left) Swimming pool at ha
Crosse. Wis. Nelson & Fuisch, Archi-
tects. Constructed by National Build-
ers Inc., Minneapolis. One cor of
Waterproofed White Portland Cement
(Center Left) Girls' Dormitory, Uni-
versity ot Michigan. Ann Arbor. Mich.
Contractor, Pehison Bros.. Minneapo-
lis, Minn. Dealer, W. H. L. Rohde, Ann
Arbor. Mich. 8 cars of Medusa Water-
proofed Gray Portland Cement used.
dower Left) Anthony Wayne Hotel
Hamilton, O. Contractor, F. K. Vaughn
Bldq. Co. Architects. Fred G. Mueller
6 Walter R. Hair, Assoc., Hamilton.
Medusa Waterproofed Gray Portland
!) WITH MEDUSA
irg. Va. Medusa Waterproofed
tnfbundations and retaining walls.
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Lambert, Barger & B-anaman Building, Waynesboro, Virginia
C. W. Hinnant, Lynchburg, Architect W. K. Smith, Jr., Associate Architect
H. S. Brooks, Waynesboro, Contractor Lambert Mfg. Co., Waynesboro, Dealer
Medusa Waterproofed Gray Portland Cement used.
Carl Hansen Laboratory, West Allis, Wisconsin
W. H. Buemming, Arch., Milwaukee, Wis. Osthoft & Peterson, Engs., Milwaukee
W. W. Oeflein, Inc., Contractor, Milwaukee, Wis.
Tews Lime & Cement Co., Dealers, Milwaukee, Wis.
Medusa Waterproofed Gray Portland Cement used.
American Telephone and Telegraph Co. Repealer station, Ridgeville, Ohio
Mills, Rhines, Bellman & Nordjott, Architects, Toledo, Ohio
W. J. Schirmer Co., Contractors. Cleveland, Ohio
Medusa Waterproofed Gray Portland Cement used in all floors,
foundations and for brick mortar.
Swimming pool, H. S. Black Estate, Mansfield, Ohio
Allhouse & Jones, Architects The Jacob Wolf Co., Contractors
Builders Supply Co., Dealers
Medusa Waterproofed Gray Portland Cement used.
SPECIFICATIONS ioi waterproofed Portland Cement Stucco
The following fundamental rules must be ob-
served in ihe production of good stucco:
a— Use a good rigid base which will not shrink,
warp, bend or deteriorate with time.
b— Use proper proportions and carefully selected
sand and aggregates of correct grading.
c— If an absorbent base, such as hollow tile, con-
crete block or brick is used, sprinkle before
applying fresh stucco.
d— All stucco coats— base or scratch coal, second
or brown coat, third or finish coat— should be
waterproofed. This is just as important in the
case of the base coat as any other, since the
base coat must not possess sufficient "suc-
tion" or absorptive tendency to take up the
water from the fresh cement plaster or stucco
coat applied to it before the cement has had
an opportunity to hydrate and set.
e-Each stucco coat must be sprinkled with
water before applying the next coat; and the
finish coat must be kept evenly moist by
sprinkling. In hoi weather the work must be
shielded from the direct rays of the sun, and
protected at all times from the wind. The im-
portance of these precautions cannot be over-
l.DESIGN-Whenever the design of the struc-
ture permits, an overhanging roof or similar pro-
jection is recommended to afford protection to
the stucco. It is well for the architect to prevent
concentration of water flow getting at the stucco
at all, so as to avoid staining of ihe finish. Stuc-
coed copings, cornices, and other exposed hori-
zontal surfaces should shed water quickly, and
whenever departure from the vertical is neces-
sary (at water tables, belt courses, and the like)
the greatest possible slope should be obtained.
Stucco should not be run to ihe ground-but
should have a water table or belt course which
is high enough above ihe ground io avoid
splashing of mud and diri upon the finished sur-
face. The backing should be of tile, brick, stone,
concrete or metal lath, providing good mechani-
cal bond for the stucco. It must be thoroughly
cleaned before plastering.
2. FLASHINGS-Suitable flashing should be pro-
vided over all door and window openings
wherever projecting wood trim occurs. Wall
copings, cornices, rails, chimney caps, etc.,
should be built of concrete, stone, terra cotta or
metal, with water-tight joints and ample over-
hanging drip groove or lip.
If copings are set in blocks with mortar joints,
continuous flashing should extend across the
wall below ihe coping and project beyond, form-
ing an inconspicuous lip over the upper edge
of ihe stucco— or the copings may be set in mor-
tar composed of Medusa Waterproofed Portland
Cement and sand. Continuous flashing with
similar projecting lip should be provided under
brick sills. This flashing should be so installed
as to insure absolute protection against in-
Cornices set with mortar joint should be pro-
vided with flashing over the top or set in mortar
composed of Medusa Waterproofed Portland
Cement and sand. Sills should project well from
ihe face of ihe stucco and be provided with drip
grooves or flashings as described above for brick
sills. Sills should also be provided with stools or
jamb seals to insure wash of water over ihe face
and not over ihe ends.
Special aitenlion should be given io ihe design
of gutters and downspouts at returns of porch
roofs where overflow would result in discolor-
ation and cracking. A two-inch strip should be
provided at ihe intersection of walls and sloping
roofs and flashing extended up and over it, ihe
stucco being brought down to ihe top of the strip.
3. PREPARATION OF ORIGINAL SURFACES-
All roof gutters should be fixed and downspout
hangers and all other fixed supports should be
put in place before the plastering is done, in
order io avoid breaks in the stucco. All trim
should be placed in such manner thai it will
show its proper projection in relation to the fin-
ished stucco surface, particularly in overcoating.
MATERIALS-The cement for ihe first coat (base
or scratch coat) and second (or brown coat) shall
be Medusa Waterproofed Gray Portland
Cement, or, if standard Gray Portland Cement
conforming to the specifications of the American
Society for Testing Materials be used, add two
per cent by weight of Medusa Waterproofing
Powder (2 lbs. per sack of cement) or Medusa
Concentrated Waterproofing Paste (0.6 lb. per
sack of cement). (See instructions on container.)
The cement for ihe third or finish coat shall be
Medusa Waterproofed White Portland Cement.
4. FINE AGGREGATE-Fine aggregate shall
consist of sand, or screenings from crushed stone
or crushed pebbles, evenly graded from fine to
coarse, passing when dry a No. 8 screen. Fine
aggregates should preferably be of siliceous
materials, clean, coarse and free from loam
vegetable or other deleterious matter.
5. HYDRATED LIME-Hydrated lime shall meet
the requirements of the standard specifications
for hydrated lime of the American Society for
6. COLORING MATTER-Only permanent, lime-
proof and sunproof colors shall be used. Finish
coats containing colors shall be applied as dry
as possible to prevent separation of the colors.
The use of Medusa Waterproofing will prevent
the gradual fading of a color surface due to a
film of efflorescence on the surface.
7. WATER-Water shall be clean, free from oil,
acid, strong alkali or vegetable matter.
PREPARATION OF MORTAR-8. MIXING-The
ingredients of the mortar shall be mixed until
thoroughly distributed and the mass is uniform
in color and homogeneous. The quantity of water
necessary for the desired consistency should be
determined by trial, and thereafter measured in
proper proportion. The water shall be added
slowly to the dry mix so as to allow the aggre-
gates to absorb as much as possible in the course
9. MACHINE MIXING-The mortar shall prefer-
ably be mixed in a suitable mortar mixing ma-
chine of the rotating drum type. The period of
machine mixing shall be not less than three
minutes after all the ingredients are introduced
into the mixer.
10. HAND MIXING-The mixing shall be done in
a watertight mortar box, and the ingredients
shall be mixed dry until the mass is uniform in
color and homogeneous. The proper amount of
water shall then be added and the mixing con-
tinued until the consistency is uniform.
11. MEASURING PROPORTIONS-Methods of
measurement of the proportions of water shall
be used which will secure separate uniform
measurements at all times . All proportions
stated shall be by volume. A bag of cement (94
lbs. net) may be assumed to contain one cubic
foot. Forty pounds may be assumed as the
weight of one cubic foot of hydrated lime.
12. RETEMPERING-Mortar which has begun to
stiffen shall not be used nor reiempered with
additional water and used.
13. CONSISTENCY-Only sufficient water shall
be used to produce a good workable consistency.
The less water in the mix, the better the quality
of the mortar, within working limits.
MORTAR COATS - 14. PROPORTIONS - All
coats shall be one pari Waterproofed Portland
Cement (white or gray) and three parts fine ag-
gregate; hydrated lime for buttering purposes
not to be in excess of 10% by weight of the
15. APPLICATION-The plaster shall be applied
with a steel trowel and carried on continuously
in one general direction without allowing the
plaster to dry at the edge. If it is impossible to
work the full width of the wall at one time, the
jointing shall be at some natural division of the
surface, such as a window or a door.
The first coat shall thoroughly cover the base on
which it is applied and shall be troweled enough
to insure the best obtainable bond. Before the
coat has set it shall be heavily cross-scratched
with a saw-toothed metal paddle or other suit-
able device to provide a strong mechanical key.
The first coat shall be kepi thoroughly wet until
the second coat is applied. The second coat shall
be brought to a true and even surface by screed-
ing at intervals not exceeding five feet, and by
constant use of straightening rod.
When the second coat has stiffened sufficiently.
it shall be dry floated with a wood float, and
evenly cross-scratched to form a good mechani-
cal bond for the finish coat.
From the time of application of the second coat
and for not less than three days thereafter, the
stucco must be kepi continuously wet by thor-
ough spraying ai frequent intervals. It shall then
be allowed to dry out ihoroughly.
The finish coat shall be applied not less than
a week after the application of the second coat.
Methods of application will hereinafter be de-
scribed under "Finish."
16. CURING-To develop maximum strength and
density in any Portland Cement product it is
necessary to cure it properly. This is especially
true of Portland Cement stucco, which is really
a thin slab of concrete. Each coat should be kept
damp continuously for at least two days. Mois-
tening should commence as soon as the stucco
«*> H„ide„c. o/ S. Goodman, (Cant.,) i^-S J- »-» ** STSff-SS^*^
Highland Par*, /]/. E. H. flabe, and E. Hou.a, Clinton. ******** %**£*** **«*. MM Ban-
(Bottom Right) JtaiJdanca of Harbor*
Holmqt—n, San Antonio. Tow. MvrrlM
£ Hoonan, ArcaJJoclf . F. O. Holtiman,
Cement used lor exterior ttueco. Gray & Whlto Portland Comon/i mod.
umd tot i/ucco.
(Top) Masonic Home, Wichita, Kan. (Center Left) Residence ox A. G (C#nt«r Hini,»\ «.. ■ -i .. „ «„.,
Hi/on & Githens. Architects. New c^ Gienco# Winoia . ° r * (Cen e r H»ght) The Anderson Memo- (Bottom) flesidence of James N- fiw-
v^-l u v « . - — i*aoie, Lriencoe, Illinois. Adler and rial in La r»u M tin. r\**- * **__ _ -
George H. Siedhoff Cons/ruciion Co.. Work ' * "J 1111 *- ^^ *&%*. Win- man. La Crosse, Archirecf. TTieo. /. Wes/er GeneFa' W Y. Plaster Con-
Gray Waterproofed Cements used in
used in srucco.
Cement used in stucco.
has hardened sufficiently not to be injured, ap-
plying the water in a fine fog spray. Avoid
soaking the wall. Give it only as much water as
will be readily absorbed. To prevent excessive
evaporation on the sunny or windward sides of
building in hot, dry weather, tarpaulins should
be hung over the outside of the stucco and
After the damp-curing period, the base coats
should be allowed to dry thoroughly before the
finish coat is applied. The practice of doubling
coats without a two-day moist-curing period fol-
lowed by a drying interval is not good construc-
tion practice. Unlike regular cements, once
waterproofed stucco dries out it repels all water
at the surface, hence cannot be wet again for
When stucco is applied during cold weather,
longer curing periods are necessary. In freezing
weather it should not be applied unless special
methods are employed to keep the materials at
a temperature above 50 degrees Fahrenheit for
at least 48 hours.
FINISH- 17. Stippled-The finishing coat should
be troweled smooth with a metal trowel with as
little rubbing as possible, and then should be
lightly patted with a brush of broom straw to
give an even stippled surface.
18. Sand Floated-The finishing coat, after being
brought to a smooth, even surface, should be
rubbed with a circular motion of a wood float
with the addition of a little sand slightly to
roughen the surface. This floating should be
done when the mortar has partly hardened.
19. Sand Sprayed— After the finishing coat has
been brought to an even surface, it should be
sprayed by means of a wide, long-fiber brush—
a whiskbroom does very well— dipped into a
creamy mixture of one part of cement to two or
three parts sand, mixed fresh at least every
thirty minutes and kept well stirred. This coating
should be thrown forcibly against the surface to
be finished. This treatment should be applied
while the finishing coat is still moist and before
it has attained its early hardening-thai is,
within three to five hours. To obtain lighter
shades, add hydrated lime not to exceed 10%
of the weight of the cement.
20. Rough-cast or Spatter Dash-After the finish-
ing coat has been brought to a smooth, even sur-
face with a wooden float, and before finally
hardened, it should be uniformly coated with a
mixture of one sack of cement to two or three
cubic feet of fine aggregate wet to the consis-
tency of cream, and thrown forcibly against it to
produce a rough surface of uniform texture when
viewed from a distance of 20 feet.
Special care should be taken to prevent the
rapid drying out of this finish by thorough wet-
ting down at intervals after stucco has hardened
sufficiently to prevent injury.
21. Cement Colors— When it is required that any
of the above finishes should be made with col-
ored mortar, not more than 10% of the weight of
portland cement should be added to the mortar
in the form of finely ground mineral coloring
matter and this quantity should replace an equal
amount of hydrated lime, instead of cement, or
used as an additional material.
A predetermined weight of color should be add-
ed dry to each batch of dry fine aggregate be-
fore the cement is added. The color and fine
aggregate should be mixed together and then
the cement mixed in.
The whole should be then thoroughly mixed dry
by shoveling from one pile to another through
a Vi-inch mesh wire screen until the entire batch
is of uniform color. Water should then be added
to bring the mortar to a proper plastering
BACKGROUNDS OR BASES
Concrete Blocks, Concrete Surfaces,
TUe and Brick
TILE-Tile shall be hard burned with dovetail or
heavy ragged scoring. Joints are not to be raked,
but cut back to the surface of tile.
Surface of tile shall be brushed free from all
dirt, dust and loose particles, and, prior to ap-
plication of stucco, shall be wet to prevent suc-
tion and absorption.
BRICK-Brick shall be rough hard burned brick,
set with %-inch joints. Joints to be raked out V2-
inch from face of brick. Surface of brick shall be
brushed free from all dirt, dust and loose parti-
cles, and prior to application of stucco, shall
Old brick walls which are to be overcoated shall
have all loose, friable or soft mortar removed
from the joints to a depth of at least half an inch.
Brick surfaces, painted or waterproofed, shall be
covered with metal lath.
Extremely soft brick must be covered with metal
lath of fine poultry wire, well stapled.
CONCRETE BLOCKS - Shall be rough and
coarse, but not friable, and set in cement mortar,
with joints raked out at least Vfe-inch deep. Sur-
faces of blocks shall be brushed free from all
dirt, dust and loose particles, and prior to ap-
plication of stucco, shall be wet.
CONCRETE SURFACES - Concrete surfaces
shall be hacked or roughened by drills, so as to
provide bond for stucco.
After hacking, surface shall be washed down
with a solution of one part muriatic acid to 10
parts water. After acid solution has exhausted
itself, surface is to be washed down, to remove
any remaining acid. Wirebrush surface so as to
remove all loose particles of concrete.
Prior to application of stucco, wet the wall so as
io prevent absorption of water from stucco, and
apply a good creamy cement grout an hour be-
fore applying stucco.
SMOOTH SURFACES-To obtain a smooth sur-
face, after troweled finish has become suffi-
ciently hard, rub carefully with a fine carborun-
dum stone and water, rinse with clean water,
grout with clear cement and allow to remain for
a week or longer; rub io smooth finish.
STUCCO ON METAL LATH
Where Sheathing Is Used
SHEATHING - Sheathing boards shall not be
less than six inches nor more than eight inches
wide, dressed on one or both sides io a uniform
thickness of 13/16 of an inch; laid horizontally
across wall studs, and fastened with not less
than two 8d nails at each stud.
Over sheathing boards shall be laid, in hori-
zontal layers beginning at the bottom, a sub-
stantial paper well impregnated with tar or
asphalt. The bottom strip shall be laid over the
baseboard at the bottom of the wall, and each
strip shall lap the flashings at all openings.
BACK-PLASTERED - NO SHEATHING - Fram-
ing-Studs spaced not io exceed 16-inch centers
should be run from the foundation io rafters with-
out any intervening horizontal members. The
studs should be tied together just below the
floor joists with 1 x 6 inch boards which should
be let into the studs on their inner side, so as to
be flush, and securely nailed io them. These
boards will also act as sills for floor joists, which
should be securely spiked to the side of studs.
BRACING-Corners of each wall shall be braced
diagonally with 1 x 6 inch boards lei into studs
on inner side, and securely nailed to them.
In back-plastered construction in which sheath-
ing is omitted at least once midway in each story
height, the studs shall be braced horizontally
with 2x3 inch bridging set one inch back of the
face of the studs. This assumes thai the siuds are
2x4 inches. Larger siges require larger bridging.
FURRING-One-half inch 22 gauge crimped fur-
ring is io be fastened direct to the studding, using
1 Va inch by 14 gauge staples placed 12 in. apart.
LATH— Expanded metal, or wire mesh, galva-
nized or painted, weighing at least 3.4 pounds
per square yard.
Metal lath shall be placed horizontally, drawn
tight, and attached with Wa inch by 14 gauge
staples, or 6d nails driven to a penetration of at
least 7 /s inch and bent io engage at least one rib,
not over eight inches o. c.
Lath shall be lapped at least two inches hori-
zontally and tied with 18 gauge black tie wire
at least once between studs. Vertical laps shall
be at least two inches and shall occur at sup-
ports. Lapped ends fastened with staples or 6d
nails not over four inches o. c.
CORNERS-The sheets of metal lath shall be
folded around the corners for at least four inches
and well stapled down in sheathed construc-
tion and one siud opening in open frame con-
Corner bead is not recommended, but a strip of
diamond mesh expanded metal, 24 gauge,
formed io a six inch angle, may be used.
INSULATION-The air space in back-plastered
walls may be divided by applying building
paper, quilting, felt, or other suitable insulating
material between the studs, fastening it to the
studs and bridging by nailing wood strips over
the folded edges of the maierial. This insulation
shall be so fastened as to leave about one inch
air space between it and stucco. Keep insulating
material clear of stucco. Make tight joints
against the framing.
BACKING COAT-Shall be applied directly fol-
lowing the completion of the brown coat. The
keys of the scratch coat shall first be thoroughly
dampened, and the backing coat well troweled
on io insure filling spaces between keys and
thoroughly covering back of lath. The backing
coat shall provide a total thickness of plaster
back of lath of % or Va of an inch.
SPECIFICATIONS for waterproofing existing concrete work
PREPARATION OF SURFACE
ON OLD CONCRETE OR CEMENT PLASTER-
The old surface shall be mechanically rough-
ened or hacked by means of stone mason's ham-
mer, drills or similar tools, exposing the mairr-
of the concrete and leaving Va inch to % inch
deep holes every two to three inches, so as lo
provide a better bond for the cement plaster.
Remove all loosened pieces and apply freely to
the cleaned area a solution of one part muriatic
acid and ten parts of water, using a fibre or acid
brush. Allow acid solution to remain until the
acid exhausts itself, approximately 10 minutes.
Wash the surface with water from a hose, being
careful to remove all of the acid solution. Go
over the walls with a stiff wire brush, or where
available, compressed air or steam may be
used, and remove any remaining loose pieces
ON BRICK, CONCRETE BLOCKS OR MASONRY
—Mortar joints shall be raked out to a depth of
Vz inch to Va inch and all old and loose mortar
removed. This is absolutely necessary in order
to give good key for the plaster. Prepare a grout
of Medusa Portland Cement and water.
Mix to a creamy consistency and apply with a
fibre brush to the cleaned surface, brushing with
grout thoroughly into the concrete for a short
distance ahead of the plaster.
All masonry surfaces shall be thoroughly satu-
rated with water before grouting is applied.
REMOVING OLD PAINT-A11 oil paint films or
whitewash must be thoroughly removed.
PROPORTIONS-The cement plaster shall be
composed of one part Medusa Waterproofed
Gray Portland Cement and two and one-half
WATERPROOFING - If Medusa Waterproofed
Cement is not available, use Medusa Water-
proofing, either Powder or Concentrated Paste,
to waterproof the portland cement employed.
Follow the simple directions on the container.
SAND— Shall be clean, sharp and free from clay,
loam, vegetable or other injurious matter, \ a inch
down in size.
MIXING— Use materials as heretofore specified,
mix the waterproofed cement plaster to a stiff,
workable consistency, adding the water slowly,
using the minimum volume of water necessary
to give a plastic mix.
Y. M. C. A. Building, Evanslon, Illinois
Chester H. Walcott, Chicago, 111, Architect N. P. Severin Co., Chicago, Contractor
Medusa Waterproofed Gray Portland Cement used in all concrete below grade and in swimming pool.
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Seville School Ross Township, Pa. Press C. Dowlei, Pittsburgh, Pa., Architect Powell Bros., New Kensington, Pa., Contractors
Medusa Walerprooted Gray Portland Cement used in brick mortar and foundation.
IN CASE WATER INTERFERES WITH THE
WORK— If there is a continual seepage through
the walls, holes must be bored in the walls and
tubes or small gas pipes inserted to concentrate
the flow of water and relieve the pressure while
the plaster coat is being applied. Caulk around
pipes with oakum or lead wool. Drainage pipes
should remain open until the waterproofed
cement plaster coat has thoroughly set and is
capable of resisting the pressure by its own ad-
hesive strength, after which remove pipes and
plug holes, covering them with waterproofed
WATERPROOFED CEMENT PLASTER
APPLICATION OF CEMENT PLASTER-Satu-
rate the entire surface with water to prevent the
surface from absorbing water from the cement
plaster before the cement has had time to hy-
drate or set.
Apply the first coat of plaster 3 /s inch thick,
troweling the plaster well into the surface so as
to secure a proper bond.
Scratch the first coat with a "scratcher." Do not
use nails or trowels, nor scratch too deep.
As soon as the first coat has set hard enough,
sprinkle with water and apply the second coat
3 /e inch thick, troweling the plaster with suffi-
cient pressure to obtain maximum density and
to close all surface pores, leaving a tight, clcse-
Where waterproofed cement plaster is to be ap-
plied to walls and floors, cut second coat of
plaster off six inches above the finished floor line.
* After the piaster coat has been applied,
applied to give better diffusion of light and
Where joints must be made in cement plaster
work, run the cement work an inch or two be-
yond the contemplated joint. After plaster has
set, cut this surplus off on as broad bevel as
possible, giving this bevel a coat of grout prior
to applying subsequent plaster.
The finished surface must be protected from too
rapid drying out, by keeping moist for at least
a week to allow it to harden thoroughly and to
prevent hair cracks. Sprinkle at frequent inter-
vals with a hose, or cover with canvas or burlap
kept continually wet.*
WATERPROOFED FLOOR TOPPING
FLOORS - Water gathering under basement
floors exerts an upward pressure which often is
strong enough to crack the concrete floor.
If existing floors have been cracked by water
under the floor, the waterproofed portland
cement lopping applied to the lop of the old
floor should be sufficiently reinforced to pre-
APPLICATION OF FLOOR TOPPING - After
walls have been plastered, prepare the surface
of floors, including the six inch base at walls, in
the same manner as walls (see "Preparation
Have floors cleaned, saturated with waler and
apply grout as described; use care to prevent
mud or dirt being tracked over the grouted sur-
face. Apply a two-inch coat of waterproofed
cement jloor topping as per specifications for
bonded concrete floor finish, page 14, joining
the covered base wilh the finished wall cement
Medusa Portland Cement Paint should be
a washable surface that is easy to keep clean.
SPECIFICATIONS foi waterproofing concrete blocks
during the process of manufacturing
The block manufacturer will find the following
specifications of value.
CEMENT— The cement used shall be Medusa
Waterproofed Gray Portland Cement.
COARSE AGGREGATE-Coarse aggregate shall
consist of clean pebbles, crushed limestone,
granite or trap rock, well graded so thai the
largest size will not exceed one third of the thick-
ness of the thinnest web of the block. Not more
than five percent shall pass a Winch screen.
FINE AGGREGATE-Fine aggregate shall con-
sist of sand or screenings from hard crushed
limestone, granite or trap rock, well graded and
free from dust, which shall pass though a Vi-inch
screen, and shall not contain more than five per-
cent of silt, loam or impurities. It should have at
least 15% retained on a Vs-inch screen.
PROPORTIONS-The mixture of waterproofed
cement, sand and stone must be such that the
block will comply with the governing Building
Code, whether city or state. In some states and
cities this requirement is a compressive strength
of not less than 750 pounds per square inch; in
other localities the requirements are 1,000
pounds or more.
The block manufacturers should experiment
with the sand and stone available until he can
give the required strength with the least amount
of cement per block. As an illustration, some
manufacturers obtain 20 or 22 blocks with block
size of 8" x 8" x 16" from one sack of cement,
whereas others, due to poorly graded aggregate,
cannot obtain more than 14 or 16 blocks per bag
of cement. In general, the coarser the grading
of aggregate the greater the strength for a given
amount of cement provided the mix is workable
in the machine. However, too coarse grading
tends toward rough surfaces and edges.
The mix for the facing on blocks shall consist
of one part Medusa Waterproofed Gray Portland
Cement and three parts of clean sand.
HAND MIXING— Dampen the sand or aggregate,
add the waterproofed cement, and mix as usual.
When sand and waterproofed cement are uni-
formly mixed, add only enough water to secure
BATCH MACHINE MIXING-Put the sand and
aggregate into the mixer with the waterproofed
cement; allow mixer to run until the cement and
sand are well mixed before adding additional
water. Mix at least one and one half minutes
after all water is added. In dry tamp method,
mix at least two minutes.
CONSISTENCY-Sufficent water shall be used
to permit the blocks to be removed from the
molds without distortion, but not so much as to
CURING-A11 concrete blocks should be thor-
oughly cured by keeping them in well built
steam kilns, by keeping them wet by the use of
fog sprays, or by sprinkling them often enough
so surfaces will not become air-dry.
Proper and thorough curing is one of the most
essential and important steps in the manufac-
ture of concrete blocks.
Send for booklet on recommended practice for
the manufacture of blocks.
Residence of Miss Anna Zolter, St. Clair River, Detroit.
Blocks supplied by State Builders Supply Co., Detroit.
SPECIFICATIONS for the waterproofing of concrete
brick and roofing tile
The manufacture of concrete brick and concrete
roofing tile has been increasing rapidly in the
last few years. Manufacturers of complete
equipment for making concrete brick and con-
crete tile have established independently owned
Concrete brick and tile have the advantage of
being lighter in weight, easier to handle and
transport, and easy to lay up, permanent, beauti-
ful and fireproof. They can be made in any range
of colors, shades and textures or combinations,
also in any size, thereby offering the builder or
architect a wide variety to meet the needs
Because the materials for manufacturing con-
crete brick and tile are universally available, the
manufacturing plants can be erected in practi-
cally any market, thereby saving tremendously
on freight and trucking charges.
SPECIFICATIONS-Aggregate used in concrete
brick shall be hard and sharp. Grading should
start with a 3 /s-inch mesh. About 5% should be
left on a Vi-inch mesh, approximately 15% on a
Va inch mesh, 15% on a 14-mesh, 25% on a 28-
mesh, 30% on a 48-mesh, 10% on a 100-mesh.
It is of course not necessary to adhere strictly
to this gradation, for there are other variations
as good but this principle applies to every kind
of concrete unit. The better the aggregate is
graded, the better the units will be.
RATIO OF MIX-The ratio of mix is one part of
Medusa Waterproofed White or Waterproofed
Gray Portland Cement to seven parts of sand,
up to one part of Waterproofed White or Water-
proofed Gray Portland Cement to ten parts cf
sand. Materials should be mixed with the water
for four minutes. In cold weather the water
should be warmed. To obtain the proper water
content, a handful of mix, stroked with the
trowel, should bring beads of moisture to the top,
KILN CURING-Cement brick gets its initial set
over night in store room. If cured in steam kilns,
the starting temperature should be 70 °, and then
run up to 100 or possibly 110°. Brick should be
kepi in this temperature over night. Wet steam
should be used at a low pressure of about five
pounds. The amount of relative humidity should
be at least 90%.
WATER CURING-Brick should stand over night
to get initial set, then pile in yard and wet down
with a hose as necessary to keep them wet con-
tinuously for at least ten days. Care should be
taken in the summer time to see that bricks do
not dry out too fast. Likewise in winter, care
should be taken so bricks do not freeze together.
The use of Medusa Waterproofed Gray or Water-
proofed White Portland Cements in making con-
crete brick and tile does not vary the specifica-
tions. Waterproofed cements are used exactly
the same way as ordinary gray cement.
Waterproofed concrete brick repels all water at
the surface and is particularly advantageous as
a means of preventing efflorescence and disinte-
gration. In unwaterproofed concrete, brick or
tile, dirt accumulates on the surface, is carried
by water when the latter is absorbed, into the
surface. If waterproofed cements are used, the
water laden with dirt cannot be absorbed into
the surface, but the dirt itself is washed off.
Waterproofing concrete brick also prevents de-
terioration due to absorbed water entering liny
crevices or pores, freezing, causing crumbling.
All water is repelled at the surface. To prevent
mortar deterioration, all concrete brick should
be laid in mortar made with Medusa Water-
proofed Portland Cement.
Natural colored Dunbnk
home in Atlanta, Georgia.
Dunbrik is used in solid
and hollow wall con-
slmction, plain or faced.
Buff mat glazed Dunbrik home
with a green mat glazed
Duntex roof, Metropolis, Illinois.
THE TWELVE MEDUSA PRODUCTS
MEDUSA GRAY PORTLAND CEMENT
A standard Gray Portland Cement guaranteed to comply with the specification requirements
of the American Society for Testing Materials.
MEDUSA WATERPROOFED GRAY PORTLAND CEMENT
Our standard Gray Portland Cement with the proper amount of Medusa Integral Water-
proofing ground in at the mill It is less expensive than adding waterproofing on the job, and
insures proper distribution. It should be used wherever concrete is below grade or exposed
to moisture or dampness.
MEDUSA "MEDCO" HIGH EARLY STRENGTH CEMENT
High Early Strength Cement has all the properties of our standard Gray Portland Cement
but with this difference-it has the normal 5 to 7 days' strength in 24 hours.
MEDUSA WHITE PORTLAND CEMENT
A standard Portland Cement used wherever Portland Cement is specified and white or
colored effects are desired-same strength as Gray Portland Cement-non-staining.
MEDUSA WATERPROOFED WHITE PORTLAND CEMENT
Our standard White Portland Cement with the proper amount of Medusa Integral Water-
proofing ground in during process of manufacture. Used for stucco and stone mortar and
all work subjected to damp or wet conditions. Non-staining.
MEDUSA STONESET CEMENT
A non-staining waterproofed mortar cement for setting, pargeting, and pointing of cut stone,
and for laying up face brick. The cost permits use for mortar in backup wall.
MEDUSA BRIKSET CEMENT
Has a Portland Cement base and is waterproofed. Obtains a high early strength which is
very important to the mason contractor. It has a very pleasing color when used natural or
with mortar colors. It is a prepared masonry mortar having minimum shrinkage; simply mix
with sand and water on the job.
MEDUSA PORTLAND CEMENT PAINT
A decorative and protective coating for all concrete and masonry surfaces. Can be applied
on fresh concrete or wet surfaces. Furnished in black, white and seven colors.
MEDUSA FLOOR COATING
A concrete floor covering that needs no undersurfacer. It is moistureproof and highly resistant
to abrasive wear, Furnished in black, white and six colors.
A flat wall finish for interior use. Comes in white and seven beautiful colors, is durable,
quick drying, economical. One coat is usually sufficient.
MEDUSA WATERPROOFING POWDER
A dry powder to be added to Portland Cement. By its use, concrete is waterproofed. It is to
be used where Medusa Waterproofed Gray Portland Cement or Medusa Waterproofed
White Portland Cement is not available. Powder is shipped in 40 lb. bags.
MEDUSA CONCENTRATED WATERPROOFING PASTE
Similar results are obtained as with the powder. It is added to the concrete mix through the
gauging water. Paste is shipped in 8 lb. and 40 lb. containers. Also furnished in 225 lb.
and 400 lb. drums.
TABLE OF CONTENTS-
Why ihe Name Medusa 3
Why Concrete, Stucco and Masonry, Including Mortar, Should be Water-
proofed During the Original Construction 5
Waterproofed Cement Has These Advantages . 6
Proving the Value of Medusa Waterproofing . . 7
Essentials of Good Waterproofed Concrete . . 8
Waterproofing Concrete and Masonry Below Grade Level 10
Protecting Above Grade Level Concrete, Masonry and Stucco Surfaces
Against Disintegration 11
Specifications for Waterproofing Concrete Foundation Walls and Basement
Specifications for Bonded Concrete Floor Finish 14
Waterproofing Mortar for Masonry 15
Specifications for Waterproofed Portland Cement Stucco 19
Specifications for Waterproofing Existing Concrete Work 25
Specifications for Waterproofing Concrete Blocks During the Process of
Specifications for the Waterproofing of Concrete Brick and Roofing Tile . . 28
The Twelve Medusa Products